The story has highlighted the need for the PR industry to sign up to a pledge to stamp out unpaid internships both in-house and in agencies.

PRWeek and the PRCA launched a campaign in October 2011 to end the practice of unpaid internships. To date 58 consultancies have signed up to the campaign, confirming that they pay interns at least the national minimum wage.

PRCA chief executive Francis Ingham, commenting on the actions of Arcadia, said: ‘This is appalling behaviour to rip off interns in this manner and Arcadia should be ashamed of itself. I very much hope that it has now put the right procedures in place so that this never happens again.

‘The joint campaign between the PRCA and PRWeek has been finding that by-and-large the PR industry is treating interns in the right way, although there’s still some way to go.

‘The PR industry needs to agree to pay interns at least the national minimum wage but also to have intern programmes that provide real training and the development of professional skills. Interns should not be used just to carry out menial tasks – they need a proper working experience.’

The Guardian has reported that Arcadia, which owns Topshop, Dorothy Perkins and Miss Selfridge, has sent hundreds of pounds worth of backdated payments to dozens of PR interns.

The report details interviews with past interns who spoke of having to ‘ship clothing back and forth to media contacts from a windowless stockroom’, spending the rest of the time photocopying and scanning images.

The interns also told The Guardian that they would be left to their ‘menial’ tasks without much supervision and then have to train other unpaid interns who would arrive at Arcadia’s head office.

Director of policy and comms Phil Morgan added: ‘There are two issues here. Firstly, interns should be paid at least national minimum wage to make them accessible to people other than those who can afford to work unpaid, and on the basic principle of paying a person for a day's work, which Arcadia has now addressed and should adopt as policy from here on.

'Secondly, internships should be a short but valuable workplace introduction to a career path. A properly structured, well thought-through internship programme should offer something meaningful. Interns should not be used as a source of free labour for menial tasks.’

The Arcadia comms team failed to respond to repeated requests for comment from PRWeek. It declined to answers questions that included: ‘How many PR interns go on to get full-time permanent positions in your organisation?’, ‘When did you stop having unpaid PR interns?’ ‘What are your plans for future PR interns?' and ‘Are you now paying PR interns minimum wage?’